The invention relates to perfusion devices and methods and, more particularly, to a micro perfusion device comprising a collecting container for obtaining at least one constituent of a body fluid using a subcutaneously positioned perfusion cannula.
A micro perfusion device such as one suitable for use in the present invention comprises a casing, a perfusate supply, an inner cannula, a perfusion cannula, a collecting container and a perfusate outlet. The inner cannula is accommodated by the casing and/or by the perfusion cannula. On a lower side of the casing, the perfusion cannula projects from the casing and surrounds the inner cannula. The inner cannula comprises two cannula openings. The cannula opening which is distal when the device is implanted, i.e., subcutaneously positioned, will be referred to as the front cannula opening, and the other cannula opening which, by contrast, is nearer the casing will be referred to as the rear cannula opening. The inner cannula encloses an inner lumen between its front cannula opening and its rear cannula opening. The inner cannula and the surrounding perfusion cannula form a co-axial flow system comprising the inner lumen and an outer lumen between the inner cannula and the perfusion cannula. A rinsing fluid, called perfusate, is supplied by the perfusate supply up to the rear cannula opening, introduced through the rear cannula opening into the inner lumen, flows through the inner lumen, leaves the inner lumen through the front cannula opening into the surrounding outer lumen (i.e., the lumen of the perfusion cannula) and flows in the outer lumen back towards the casing, enters the outlet and lastly passes through the outlet into the collecting container.
In known perfusion or dialysis devices, the perfusate is conveyed by means of pumps which are arranged selectively or in combination in the perfusate supply or in the perfusate outlet and convey the perfusate into the collecting container via the perfusion supply and the two lumens. Power sources and control systems are provided for such conveying systems.